1. Field of the Invention
The present invention relates to a printer which is capable of carrying out a double face printing.
2. Description of the Related Art
A double face printer in which it is possible to print characters and/or images on both surfaces of a printing medium such as a printing paper has hitherto been known. For instance, in a certain double face printer, one surface (front surface) of a printing paper is printed by a printing head, the printing paper is turned over by a switch-back mechanism, the paper is sent once again to the printing head, and the other surface (rear surface) of the printing paper is printed.
Moreover, a printer in which a rear surface of the printing medium is turned over by using a drum which rotates while holding the printing medium has also been known. For example, another double face printer includes two vacuum drums which are rotatable, and two ink-jet heads which are arranged facing the two vacuum drums respectively. A mechanism for attaching the printing paper (printing medium) is provided to each of the vacuum drums. Concretely, a plurality of holes is provided in an outer peripheral surface of each of the vacuum drums, and the plurality of holes communicates with a plurality of air chambers provided in the drums. Moreover, the plurality of air chambers is provided with a plurality of valves for switching between communicating condition and cut-off condition with a suction source. Therefore, it is possible to generate a vacuum condition independently for each of the plurality of air chambers by the plurality of valves, and to attach the printing paper to a predetermined area of the outer peripheral surface of the vacuum drums.
In this double face printer, firstly, while the printing paper is attached to one of the vacuum drums to hold the printing paper, and while the vacuum drum is rotated, printing is carried out on one surface (front surface) of the printing paper by one of the ink-jet heads facing this vacuum drum. Next, the printing paper having the front surface printed is passed on to the other vacuum drum while turning over the printing paper. Furthermore, while the printing paper is attached to the other vacuum drum and while the other vacuum drum is rotated, printing is carried out on the other surface (rear surface) of the printing paper by the other ink-jet head facing this vacuum drum.